The essential thrust of these investigations will be to continue the definition of prodromes to ventricular fibrillation (VF) so as to permit identification of the subject at risk of sudden death. Critical in our thinking is the state of electrical instability of the myocardium. Such instability is favored by neural, neurohumoral, electrolyte and hemodynamic factors. In addition to evolving methods for exposing electrical instability, the goals will be to develop methods for protecting against sudden death. Specific objectives will include: 1) Optimization of the R/T pulsing technique for assessing the VF threshold; 2) Exploration of the role of narcotic and tranquilizing drugs on the vulnerable threshold; 3) Determination of the role of the vagus in the conscious animal with acute myocardial ischemia; 4) Assessment of the role of hypertension in modifying susceptibility to VF. Human studies will extend the technique of acute drug testing to the beta adrenoceptor blocking drugs and will determine the value of trendscription as a method for arrhythmia screening. A further intent is to develop a community cardiology program focused on preventative measures. BIBLIOGRAPHIC REFERENCES: Thompson, P. and Lown, B.: Coronary occlusion before, during and after strenuous exercise. Cardiovasc. Res. (In press, 1976). Lown, B., Temte, J.V., Reich, P., Gaughan, C., Regestein, Q., and Hai, H.: The basis for recurring ventricular fibrillation in the absence of coronary heart disease and its management. New Eng. J. Med. (In press, 1976).